Tuning mechanism for radio receivers



July* Z8, 1942. A; w. PLENSLER 2,291,532

TUNING MECHNISM FOR RADIO RECEIVERS Original Filed March 8, 1958 y 32 .2. 2.9367 l 47 f2 l @y l 367 39 Hlllln j, mmm# Q35 Patente-d July 28, 1942 TUNING MECHANISM FOR RADIO RECEIVERS Alexander W. Plensler, Chicago, Ill., assigner to Belmont Radio Corporation, Chicago, Ill., a corporation of Illinois Original application March 8, 1938, Serial No.

194,634. Divided and this application September 30, 1939, Serial No. 297,405

3 Claims.

This invention relates-to tuning devices of the type commonly known as automatic tuning devices in which the pressing of a button automatically tunes a radio receiving set to the desired frequency corresponding to the station for which the button is marked. More particularly, the invention relates to automatic tuning devices of a mechanical nature in which the force applied to the button supplies the rotative force for turning the tuning condensers. This is a divisional case from application Serial No. 194,634, filed March 8, 1938.

Quite a few automatic mechanical tuning devices have been proposed and one which has been found to be satisfactory is the type disclosed in one .of my prior copending applications, which has now issued as Patent No. 2,130,153, in which a heart-shape cam is preset by holding it in its actuated position by pressing a roller against it and rotating the tuning condensers to tune in a particular station so that the set may subsequently always be tuned to that station. In all such tuning devices there are various problems to be solved, particularly the problem of providing dependability and ease of operation with a simple and inexpensive structure. This problem was quite satisfactorily solved by my copending application mentioned. The present application is concerned with inventions which comprise further satisfactory solutions of this problem.

According to the present invention a push button which has a simple straight actuating movement similar to that of ordinary electric switch push buttons, but a little longer, is slidably mounted for linear movement in the radio receiver. The linearly movable push button is operatively connected with a lever mounted independently of the push button structure and adapted to engage a control member mounted on a rotary shaft and having cam portions extending laterally from the shaft. The rotary shaft is connected to resonance frequency changing means for the radio receiver and the control member on the shaft is moved by the lever to in turn move the rotary shaft to a predetermined tuning position. In the event that the lever and control member alone will be insufficient for moving the rotary shaft an angular distance corresponding to the limits of the resonance frequency changing means, suitable gearing may be employed intermediate the rotary shaft and such means.

The objects of the invention are for the most part apparent from the foregoing discussion, b-ut further objects and advantages will be evident from the following description and from the drawing, in which:

Fig. l is a fragmentary plan View of one form of the invention chosen for illustration.

Fig. 2 is a sectional View taken/approximately on the line 2 2 of Fig. 1.

Fig. 3 is a fragmentary View of a modified form of the invention showing the tuning structure in an intermediate tuning position.

Fig. 4 illustrates the structure of Fig. 3 predetermined tuned position.

Fig. 5 is a fragmentary plan view of the tuning structure of Fig. 3.

This divisional application is directed particularly to the structure .of Figs. 3 and 4, but for clearer understanding of the invention the structure of Figs. 1 and 2 of the original application is included. The tuning structure of the present lila invention is illustrated with representative resonance frequency changing means which inclu-des a tuning condenser having a fixed frame II and a rotatable shaft I2, rotatable through to provide the full range of tuning. The condenser, or in reality the bank of condensers, carried by the frame I I may be appropriately connected into a radio receiving set. In the structure shown in Figs. l and 2 the shaft I2 carries a pinion I3 which meshes with a gear segment I4 by which the condenser is turned to tune the receiving set to a given frequency. The gear segment I4 is carried by a counter-shaft I6 to which it is keyed, the counter-shaft being journaled in the support plates I'I, and being rotated by push buttons I8 in a manner to be described.

The shaft I6 also carries a plurality of rocker arms or control members 2|, one for each key I8. These rocker arms are normally heldin Xed relationship to the shaft by friction means including washers 22 which are keyed to shaft I6 and clamped against the rockers or control members 2| by means of spacing collars or bushings 23. and 24. The clamping force may be exerted on the bushings 23 and 24, and washers 22, and hence on the rockers 2| simultaneously in any suitable manner as by letting the bushings bear against a screw 26 at one end of the shaft and screwing a thumb screw 2'I on the other end of the shaft. Suitable clamping means are also more fully described in the patent noted above. The thumb screw 2l obviously clamps all of the bushings together and against the screw 26. When the thumb screw 2'I is loosened, the rockers 2i may be adjusted independently to different positions on the shaft I6 so that they may be used to tune the receiving set to different stations.

Sufficient pressure is maintained to hold the rockers temporarily in any position by a spring washer 28 and the support plates Each of the push buttons |8 is carried by an actuator 29 which includes the two legs 3|, on each of which is formed a pressure arm 32 positioned to engage the arms of the rocker 2| at Widely spaced points. When the key |8 is depressed, its arm 32 will shift the associated rocker 2| to the vertical position as shown in Fig. 2. If the rocker 2| were initially inclined in one direction away from the vertical position of Fig. 2, the arm 32 on the corresponding side of the actuator would strike it first, while if it were initially inclined in the other direction the other arm would strike it first. Whichever arm strikes the rocker 2| first will rotate the rocker 2| until the other arm 32 strikes the rocker 2|, to prevent further rotation of the rocker 2 This will of course prevent the button I8 from being pressed in further and when the finger is released from button I8, it and the actuator 29 will be returned to the original position by a return spring 33. A rubber collar or felt washer 34 may be provided on shank 29 to form a cushion between the enlarged inner end of actuator 29 and the frame 36 through which the actuator 29 slides and to which the return spring 33 is secured.

In the structure illustrated in Figs. 1 and 2, the actuator 29 is guided in a very accurate and simple manner by passing its legs, which are formed by its bifurcation, through a groove 38 in the bushing 23. This not only maintains the actuator 29 in proper vertical position with respcct to shaft |6 but also maintains it in the proper longitudinal position along the shaft I6 with respect to the rocker 2|. The button-carrying shank of actuator 29 should slide snugly in frame 36 or be biased against pivoting about shaft |6 by spring 33, In view of this accurate guiding of the actuator 29 we may be sure that if a rocker 2| is properly preset on the shaft I6, depressing the corresponding button I8 will accurately tune in the desired station.

To preset the rocker 2| on the shaft I6 for tuning in a given station, the thumb screw 2'! is first loosened and the button |8 corresponding to the rocker 2| to be adjusted is depressed to bring the rocker 2| to its actuated position shown in Fig. 2. The shaft |2 is then turned manually in any suitable manner as by manipulation of a knob 39 'keyed to an extension of shaft I2 to tune the receiving set to the desired station. The button |8 may then be released and, unless other rockers 2| are to be similarly preset, the thumb screw 21 may be tightened to lock all of the rockers 2| in fixed position on the shaft I6. Depressing the same button I8 will thereafter always return the same rocker 2| to its actuated position and hence tune the receiving set to the same desired station.

Figs. 3 and 4 illustate the invention with which this divisional application is principally concerned. This structure includes a linearly movable actuator with a pivotal lever which is movableindependently of the actuator. A button 6| is mounted directly in the cabinet wall 62, being retained therein by a head on one end and a C-washer 63 snapped in a groove on the other end. Providing such a simple push-button structure and mounting therefor reduces the space necessary for the automatic tuning apparatus making the structure of my invention particularly useful and practical for small, low-priced table or portable receivers. The button 6| presses against an actuator bar or lever 64 which may be pivoted at 66, preferably to some structure, such as the cabinet, which is independent of the chassis so that the chassis may be removed from the cabinet 62 separately. This structure with the push button independent of the lever, and the latter directly accomplishing rotation of the control member permits greater manufacturing tolerance and facilitates assembly to materially reduce the average cost of the apparatus. The actuator 64 may be drawn to its inactive position by a return spring 6'| which presses the button 6| to its inactive position also. The actuator .bar .or lever 64 extends laterally in opposite directions from a point corresponding to the axial center vof a rocker or control member 68 mounted on a rotary shaft 69 which in turn is rotatably mounted in supporting plates 19. The rocker 68 may be very similar in its mounting and in its associated parts to rocker 2| of Fig. l. Whenever a push button 6| is pressed, it will press the actuator 64 against one end of the rocker 68 and this end of the rocker 68 will be pressed rearwardly until the parts come to rest at the position shown in Fig. 4. The use of the pivoted actuator 64 avoids all danger of irregularity in automatic tuning due to loose fitting of the actuator in sliding guideways. Furthermore, with the actual tuning positioning being accomplished by the lever or actuator 64, and the button 6| being movable independently thereof, movement up or down of the button due to play in its mounting wont disturb a predetermined tuning position of the control member 68, making the apparatus accurate in operation and practical under all operating conditions. It will be understood, of course, that in the structure of Figs. 3 and 4 there will normally be a plurality of rockers with a separate push button for each and that, as in Figs. l and 2, the rockers may be preset to any desired position on their respective shafts so that, when actuated, each will tune the receiving set to a diiferent station.

From the foregoing it is seen that automatic mechanical tuning apparatus has been provided in which the structure is quite simple and yet thoroughly reliable and easily operated, the push button of such structure having a simple in-andout movement.

The disclosures of this application are illustrative and the invention is not to be limited by them. In fact, if modifications or improvements are not at once obvious, they may be devised in the course of time to made additional use of the broad ideas taught and covered by this application. The claims are intended to point out novel features and not to limit the invention except as may be required by prior art.

I claim:

1. A tuning apparatus for a radioreceiver including in combination a rotary control member having an axis, said control member having control portions extending in two substantially oppositely disposed directions from said axis, a second axis remote from said first axis, elongated means pivotally mounted at one end on said second axis for originally engaging one control portion or the other of the control member to rotate said control member to a predetermined angular position, actuator means for engaging said pivotally mounted means near the other end thereof to bring the latter into contact with and rotate said control member, and means supporting said actuator means for linear movement in a plane including said first axis.

2. Tuning apparatus for a radio receiver in'- cluding in combination a rotary control member having an axis, said control member having control portions extending away from said axis in two directions, a second axis remote from said first axis but parallel therewith, a lever pivotally mounted at one end on said second axis for originally engaging one control portion or the other of the control member to move said control member to tuning position, with the opposite end of said lever extending to one side and beyond said control member, actuator means operatively engageable with said lever at said opposite end to pivot the same, means slidably supporting said actuator means for linear movement in substantially the plane of said rst axis member, and spring means connected at one end to said lever for pulling said lever and actuator means therewith away from said control member to a normally idle position.

3. Radio tuning apparatus having a chassis and a chassis housing, said apparatus including a tuning shaft, means rotatably supporting said tuning shaft on said chassis, a rocker on said shaft extending in two directions therefrom, a second shaft in spaced parallel relation with said first shaft mounted in said chassis housing, operator means pivotally supported on said second shaft having rocker engaging portions for engaging the two extending portions of the rocker to always move said rocker to the same position to turn the tuning shaft, actuator means for engaging and operating said operator means, and means slidably supporting said actuator means in said chassis housing so that said chassis with the rocker and tuning shaft thereon may be removed from the chassis housing independently of said actuator and operator means.

ALEXANDER W. PLENSLER. 

